| MIGRATORY ECTOPARASITES - | |
| Ring (Criconemella sp. ) | 19%* |
| Dagger (Xiphinema americanum ) | 17% |
| Pin (Paratylenchus sp. ) | 6% |
| Spiral (Helicotylenchus sp.) | 2% |
| MIGRATORY ENDOPARASITE - | |
| Lesion (Pratylenchus sp. ) | 51%* |
| SEDENTARY ENDOPARASITE - | |
| Root knot (Meloidogyne sp.) | 15%* |
| *LIKELY TO CAUSE DAMAGE |
The percentages add up to more than 100 because it is not uncommon for an orchard to be infested with more than one species of nematode.
Only three of the six genera, however, are likely to cause problems on walnuts.
In the case of walnuts and other perennials, it is important to try to obtain a species identification for lesion nematode. Only one species (P. vulnus) out of the six known to be present in California has been shown to cause damage.